Contour lock guides

ABSTRACT

Provided herein are patient-specific surgical guiding tools for positioning on a socket of a ball-and-socket joint, e.g. a glenoid cavity. The guiding tools comprise a central contact element fitting within the socket and one or more lateral contact elements fitting on the rim of the socket. The guiding tools allow accurate positioning of surgical tools such as alignment elements, according to a pre-operational planning. Methods for the manufacture and use of said guiding tools are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation under 35 U.S.C. §120 of InternationalApplication No. PCT/EP2012/068540, filed Sep. 20, 2012 (and published bythe International Bureau as WO 2013/041622 on Mar. 28, 2013), whichclaims the benefit of U.S. Provisional Patent No. 61/537,165, filed Sep.21, 2011. Each of the above-referenced patent applications is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Provided herein are patient-specific surgical guiding tools forpositioning on a socket of a ball-and-socket joint, e.g. a glenoidcavity. The guiding tools allow accurate positioning of surgical toolssuch as alignment elements, according to pre-operational planning.Methods for the manufacture and use of the guiding tools are alsoprovided.

2. Description of the Related Technology

In most joint arthroplasty, replacement and/or reconstruction surgeryprocedures, the joint is replaced by a prosthetic implant. The main goalof such interventions is to relieve (arthritic) pain and/or to restoresevere physical joint damage. When a prosthesis fails, a revisionsurgery is carried out. However, this procedure is technically moredifficult and time-consuming than the primary intervention and theoutcome is often less satisfactory. Furthermore, with each successivejoint revision, the risk of infection and symptomatic loosening of theprosthesis may increase substantially. Accordingly, one of the mostimportant aspects of joint surgery procedures is the correct, accurateand stable placement of the primary implant.

In order to improve the accuracy of surgical procedures in general,various custom made, patient-specific orthopedic guides are available.These custom guides may be used to accurately place pins, guide bonecuts, and insert implants during orthopedic procedures.

Typically, the guides are made from a pre-operative plan formed from anMRI or CT scan of the patient and rely on the matching of a subcutaneousanatomic feature for correct positioning of the guide according topre-operational planning. Typically, these guides rely on a directsurface contact with the defined anatomy. The contact surface isgenerally bone and/or cartilage, although guides contacting other softtissues than cartilage have been developed.

However, certain anatomies cannot be contacted with a surface matchedguide because the exact tissue shape cannot be determined, the tissue istoo soft to provide a stable position for the guide, and/or the tissuesare too vulnerable to be contacted with the guide. For example, surgicalguides for use in shoulder joint surgery cannot fit accurately onto theglenoid labrum which surrounds the glenoid fossa. This makes itdifficult to design compact and accurate surgical guides for shoulderjoint surgery, especially because the surface of the glenoid fossaitself is not adequate to achieve a unique fit position.

Accordingly, there is a need for improved surgical guiding tools forjoint surgery.

SUMMARY

The present application relates to surgical guiding tools forpositioning on the socket of a ball-and-socket joint which do notrequire any contact with the socket labrum or ligaments. The currentapplication provides a device and method for creating a locking positionover such anatomies by using the contour of the anatomy and avoiding theuntouchable surface. This contour thus provides a rotational lock bycreating a surface which contacts the contour of the anatomy, but doesnot require a surface fit in this region.

In a first aspect, provided herein is a patient-specific surgicalguiding tool for positioning an alignment element on the socket of aball-and-socket joint, or into the bone surrounding the socket,comprising a central contact element which fits onto an area within thesocket of the ball-and-socket joint and one or more lateral contactelements which fit onto the rim of the socket and/or the bonesurrounding the socket and/or the ligament around the socket. Theguiding tool may further include a positioning element provided with anopening which allows the insertion of the alignment element. In someparticular embodiments, the elements are provided as one integratedstructure for simultaneous positioning on the bone. Optionally, thecentral and lateral contact elements are provided as one integratedstructure and the positioning element is removably attached thereto.

In particular embodiments, the guiding tool as described hereincomprises one lateral contact element corresponding to at least part ofthe outer contour of the socket and the central contact elementcorresponds to at least part of the inner contour of the socket. Inparticular embodiments, the one or more lateral contact elements aredesigned to contact the rim of the socket of the ball and socket jointin at least three contact points, wherein the angle between a first lineconnecting one contact point and the center of the circle or ellipsebest fitting the rim of the socket and a second line connecting theadjacent contact point and the center is never greater than 180 degrees.

In some embodiments, the guiding tool comprises at least two lateralcontact elements which fit onto areas around the socket in at leastthree contact points, wherein the angle between a first line connectingone contact point at the center of the circle or ellipse best fittingthe rim of the socket and a second line connecting the adjacent contactpoint and the center is never greater than 180°.

In certain embodiments, the at least three contact points arerepetitively provided onto the one or more lateral contact elements,over a distance of at least 5 mm. In further embodiments, the at leastthree contact points are repetitively provided over a distance of atleast 5 mm along the direction of the longitudinal axis of the openingof the positioning element. In further embodiments, the at least threecontact points are repetitively provided over a distance of at least 5mm, 7 mm, 10 mm or 15 mm along the direction of the longitudinal axis ofthe opening of the positioning element.

In particular embodiments, the guiding tool as described herein furthercomprises a connecting structure, wherein the lateral connectingelements extend from the connecting structure. In further embodiments,the connecting structure corresponds with the positioning element.

In certain embodiments, at least one of the one or more lateral contactelements is further positioned on the guiding tool such that, whenpositioned on the bone, it interacts with an anatomical feature aroundthe socket. In particular embodiments, the alignment element is selectedfrom the group comprising a pin, a wire, a screw and a drill. Moreover,the positioning element corresponds to one of the central or lateralcontact elements. In certain embodiments, the guiding tool as describedherein is manufactured via additive manufacturing.

In still other embodiments, a further aspect provides a method for themanufacture of a guiding tool comprising obtaining volume information ofthe socket of a ball-and-socket joint from a patient and obtaining theinstallation direction of a socket implant for the patient. The methodfurther may include identifying and selecting parts of the bonesurrounding the socket which are suitable for lateral contact elementsand designing and producing a surgical guiding tool based on theobtained volume information and installation direction.

In yet another embodiment, a methods for positioning an alignmentelement into the bone of a socket or into the bone surrounding thesocket are provided. The method may include positioning a surgicalguiding tool onto the socket and using the hole provided by thepositioning element of the guiding tool to insert the alignment elementinto the bone of or around the socket. The guiding tool may then beremoved from the socket. In some embodiments, the removal of the guidingtool from the socket may include removing the guiding tool along thedirection of the longitudinal axis of the alignment element.

The patient may be an animal or human patient. Therefore the socket maybe any socket of a ball-and-socket joint in an animal or human body. Inhuman patients, the socket of a ball-and-socket joint may be a glenoidcavity or an acetabulum. In particular embodiments, the socket is aglenoid cavity.

The design of the patient specific surgical guiding tools as describedherein ensures that the guiding tools, and therefore also the alignmentelement, can be accurately positioned onto a socket of a ball-and-socketjoint without contacting the ligaments surrounding the socket. Thecontact with the contour of the socket structure provides a rotationallock of the guide, whereas the fit on the socket cavity ensures thecorrect depth position of the guide.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description of the figures of specific embodiments ismerely exemplary in nature and is not intended to limit the presentteachings, their application or uses. Throughout the drawings,corresponding reference numerals indicate like or corresponding partsand features.

FIG. 1A is a perspective view of a ball-and-socket joint (3) and theglenoid cavity (2) of a ball-and-socket joint (3).

FIG. 1B is a perspective view of a surgical guiding tool (1) accordingto a particular embodiment, positioned on a glenoid cavity (2) of aball-and-socket joint (3).

FIG. 2A is a side view of a surgical guiding tool (1) according to aparticular embodiment, positioned on a glenoid cavity (2) of theball-and-socket joint (3).

FIG. 2B is a top view of a surgical guiding tool (1) according to aparticular embodiment, positioned on a glenoid cavity (2) of aball-and-socket joint (3).

FIG. 3A is a perspective view of a surgical guiding tool (1) accordingto a particular embodiment.

FIG. 3B is a perspective view of a surgical guiding tool (1) accordingto a particular embodiment.

FIG. 3C is a perspective view of a surgical guiding tool (1) accordingto a particular embodiment.

FIG. 4 is an illustration of a glenoid for which (A) an outer contoursurface (4) and (B) a contour line (5) has been determined.

FIG. 5 is an illustration of the position of the surgical guiding tool(1) onto the glenoid and the contact it makes with the outer surface ofthe glenoid socket.

In the figures, the following numbering is used 1—ball-and-socket joint;2—glenoid cavity; 3—surgical guiding tool; 4—contour surface; 5—contourline.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

The present invention will be described with respect to particularembodiments but the invention is not limited thereto but only by theclaims. Any reference signs in the claims shall not be construed aslimiting the scope thereof.

As used herein, the singular forms “a”, “an”, and “the” include bothsingular and plural referents unless the context clearly dictatesotherwise.

The terms “comprising”, “comprises” and “comprised of as used herein aresynonymous with “including”, “includes” or “containing”, “contains”, andare inclusive or open-ended and do not exclude additional, non-recitedmembers, elements or method steps. The terms “comprising”, “comprises”and “comprised of when referring to recited members, elements or methodsteps also include embodiments which “consist of the recited members,elements or method steps.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequential orchronological order, unless specified. It is to be understood that theterms so used are interchangeable under appropriate circumstances andthat the embodiments described herein are capable of operation in othersequences than described or illustrated herein.

The term “about” as used herein when referring to a measurable valuesuch as a parameter, an amount, a temporal duration, and the like, ismeant to encompass variations of +/−10% or less, preferably +1-5% orless, more preferably +/−1% or less, and still more preferably +/−0.1%or less of and from the specified value, insofar such variations areappropriate to perform. It is to be understood that the value to whichthe modifier “about” refers is itself also specifically, and preferably,disclosed.

The recitation of numerical ranges by endpoints includes all numbers andfractions subsumed within the respective ranges, as well as the recitedendpoints.

All documents cited in the present specification are hereby incorporatedby reference in their entirety.

Unless otherwise defined, all terms used herein, including technical andscientific terms, have the meaning as commonly understood by one ofordinary skill in the art. By means of further guidance, definitions forthe terms used in the description are included to better appreciate theteaching herein. The terms or definitions used herein are providedsolely to aid in the understanding of the application.

The present application provides in a patient-specific surgical guidingtool for positioning an alignment element and/or for guiding a surgicalinstrument. The alignment element may be used for indicating a(pre-operationally planned) direction and/or position for an implant.The guiding tool comprises patient specific contact elements, which fitonto areas on and/or around a socket; the guiding tool further comprisesat least one positioning element for positioning the alignment element.

The devices envisaged herein are of particular interest to the field ofimplant surgery, more particularly in the context of implants which areplaced into a socket of a ball-and-socket joint. For human patients,this is a glenoid implant and/or an acetabular cup implant. The term“glenoid implant” as used herein refers to a component of a prostheticshoulder implant which is placed into or onto the glenoid cavity of apatient. Such implants may be used in a (total) shoulder arthroplasty orreverse (total) shoulder arthroplasty. The glenoid cavity, also known asglenoid fossa (of the scapula), is a shallow surface, which is locatedon the lateral angle of the scapula. This cavity forms the glenohumeraljoint along with the humerus. The term “acetabular cup implant” as usedherein refers to the component of a prosthetic hip implant which isplaced into the acetabulum of a patient. The acetabulum is a concavesurface of the pelvis, where the head of the femur meets with thepelvis, thus forming the hip joint. The term “contour, as used hereinrefers to the outline of an anatomical feature, typically represented bythe edge or line that defines or bounds the shape of the anatomicalfeature. For a socket anatomy the contour line may coincide with the rimor edge of the socket. Contour surfaces include surfaces extending fromthe contour line towards the inside of the socket, also referred to asinner contour surface, while outer contour surfaces are referred to assurfaces extending from the contour line outwards and typically compriseanatomical areas outside the socket.

The terms “rim” and “socket rim” as used herein refer to the edge of asocket. Usually, this is a substantially convex edge of the concave bonesurface which forms the socket. For human patients, particular examplesare the glenoid rim and/or the acetabular rim. The term “glenoid rim” asused herein refers to the edge of the glenoid cavity, more particularlythe substantially convex edge of the concave surface of the scapulawhich forms the glenoid cavity. The term “acetabular rim” as used hereinrefers to the edge of the acetabulum, more particularly thesubstantially convex edge of the concave surface of the pelvis whichforms the acetabulum.

The term “socket” as used herein in the context of a ball joint, refersto a socket of a ball-and-socket joint of the human or animal body. Forhuman patients, typical examples include the glenoid cavity and/or theacetabulum.

The term “alignment element” as used herein refers to an element whichfacilitates the correct positioning of an implant into or onto ananatomical socket, for example by indicating a certain location and/ordirection for positioning and/or by physically guiding the implant or animplant guide to a certain location. Without such element, the implantmay be positioned incorrectly, leading to suboptimal functioning of theprosthesis and discomfort to the patient.

The terms “surgical guiding tool” and “guiding tool” as used hereinrefer to (patient-specific) surgical tools that can be positioned ontoan anatomical part of a patient and that help a surgeon in thepositioning of an alignment element and/or other surgical instruments.Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, appearances of the phrases “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily all referring to the same embodiment, but may. Furthermore,the particular features, structures or characteristics may be combinedin any suitable manner, as would be apparent to a person skilled in theart from this disclosure, in one or more embodiments. Furthermore, whilesome embodiments described herein include some but not other featuresincluded in other embodiments, combinations of features of differentembodiments are meant to be within the scope of the invention, and formdifferent embodiments, as would be understood by those in the art. Forexample, in the following claims, any of the claimed embodiments can beused in any combination.

The present application provides surgical guiding tools for facilitatingthe positioning of an implant into or onto a socket of a ball-and-socketjoint in the body of an animal or human patient. More particularly, inthe context of humans, provided herein are surgical guiding tools forpositioning an alignment element, which can be used for positioning aglenoid implant or an acetabular cup implant. However the surgicalguiding tools described herein are equally useful for use in animals.

The surgical guiding tools as described herein comprise at least onecentral contact element and one lateral contact element. Together, thecentral and lateral contact elements ensure the correct positioning ofthe surgical guiding tool by contacting specific locations on thepatient's anatomy. In the surgical guiding tools envisaged herein, thecentral and lateral contact elements are typically integrated in aone-piece structure which is made to specifically fit an individualpatient's anatomy.

The central contact element of the guiding tool as described herein isprovided with a patient-specific surface which fits onto an area withina patient's socket, hereinafter also referred to as “socket contactarea”. The socket contact area typically spans an area which variesbetween one square micrometer (μm2) and fifty square centimeters (cm2).In particular embodiments, the socket contact area corresponds to atleast 10, 20, 30, 40, 50, 60, 70, 80 or 90 percent of the total socketarea. In certain embodiments, the socket contact area corresponds to thetotal area of the socket. The central contact element may provide anindication of the planned position of the guiding tool on the socket.However, the concave surface of the socket alone typically is notsufficient to provide a stable and/or unique fit position. In order toensure a stable and unique fit position, the guiding tool as describedherein further comprises one or more lateral contact elements connectedthereto, which fit onto specific areas around the socket.

Thus, the central and lateral contact elements ensure the correctpositioning of the guiding tool according to pre-operational planning.

However, the socket is typically surrounded by a (fibro)cartilaginousrim, which does not provide reliable or useful areas for contacting.This cartilaginous rim is typically referred to as socket “labrum” or“ligament(s)”, e.g. the glenoid labrum or the acetabular labrum. Wherethe socket labrum does not provide any useful areas for contacting, thelateral contact element(s) fit onto the anatomy surrounding both thesocket and the socket labrum.

In order to ensure stability of the guiding tool when positioned on thesocket, the lateral contact elements typically are designed to contactthe outer contour of the acetabular rim. In particular embodiments thelateral contact elements contact the acetabulum exclusively on theexterior of the acetabulum. In some embodiments, the contact elementscan extend over the acetabular labrum and a section of the exterior ofthe acetabulum. In further particular embodiments one or more of the oneor more contact elements can extend (transversally to the socket) fromthe interior surface of the socket towards the exterior surface of thebone comprising the socket.

The one or more lateral contact elements can be designed to make contactwith the acetabulum in either discrete contact points spread over therim of the socket which are interconnected or in a continuous elementextending over a section of the rim of the socket. In particularembodiments, the one or more contact elements extend (longitudinallyfollowing the rim of the socket) over a section of the socket rim orlabrum, more particularly over an section corresponding to 30° or more,45° or more, more particularly 60° or more and more particularly 90° to120° of the contour of the socket.

In further particular embodiments, one contact element is provided whichcontacts the acetabulum over an angular area of between 45° and 120° ofthe contour of the socket. In particular embodiments, the lateralcontact elements fit onto specific areas of the rim of the socket in atleast three discrete (i.e. non-continuous) contact points which arespaced apart on the rim of the socket. In particular embodiments, thecontact elements are distributed over at least a section of the rim soas to ensure that when the guiding tool is positioned onto the socket, arotational stability is obtained.

In a particular embodiment, the contact points have an arrangement so asto surround the socket and the socket labrum, whereby the angle betweenthe line connecting one contact point and the center of the circle orellipse best fitting the socket rim, and the line connecting theadjacent contact point and the center of the circle or ellipse bestfitting the socket rim is never greater than 180°.

In particular embodiments, the angle between the contact points (asdetermined by lines connecting each contact point with the center of thecircle of ellipse) is never greater than 175, 170, 165, 160, 155, 150,145, 140, 135, 130, 125, 120, 115, 110, 105, 100, 95 or 90°. This willbe explained in further detail herein below.

In particular embodiments, guiding tools are provided wherein thecontact points have a circular or substantially circular arrangement,preferably so as to surround the acetabulum, wherein the angle definedby two adjacent contact points is never greater than 180°. In otherwords, the angle between the line connecting one contact point and thecenter of the circle best fitting the acetabular rim and the lineconnecting the adjacent contact point and the center is never greaterthan 180°. Hereby the acetabulum is considered to have a substantiallycircular shape.

The glenoid cavity on the other hand, can be considered piriform. Thus,the glenoid cavity comprises a substantially circular shape on one side,but tapering towards the other side. Therefore, to ensure positionalstability of the guiding tool onto a glenoid cavity, guiding tools maybe provided wherein the contact points have a circular or substantiallycircular arrangement around the circumference of the rim of the glenoidcavity. More particularly, the angle formed by a first line drawnbetween one contact point and the center of the circle best fitting the(substantially circular part of) the glenoid cavity rim and a secondline drawn between the adjacent contact point and the center is nevergreater than 180°. This can also be expressed in terms of the sectorangle defined by two adjacent contact points which is never greater than180°. Alternatively, the glenoid cavity may be considered as having aroughly elliptical shape. In that case, to ensure positional stabilityof the guiding tool onto a glenoid cavity, the contact points have anarrangement, wherein the angle θ between the (straight) line connectingone contact point and the center of the ellipse best fitting the glenoidcavity rim and the (straight) line connecting an adjacent contact pointand the center is never greater than 180°. Again this can be expressedby the fact that the sector angle defined by two adjacent contact pointsis never greater than 180°.

Thus, more generally for an undefined socket, in particular embodimentsof the guiding tools as described herein, the lateral contact elementsfit onto areas surrounding the socket and socket labrum in at leastthree contact points, wherein the contact points have an arrangement soas to surround the socket, wherein the angle between a line drawnbetween one contact point and the center of the circle or ellipse bestfitting the socket rim and a second line drawn between an adjacentcontact point and the center is never greater than 180°; or similarly,the sector angle defined by two adjacent contact points is never greaterthan 180°. These contact points may all be located on the same lateralcontact element (i.e. one contact element comprises these three contactpoints), or distributed over two or more lateral contact elements.

In particular embodiments, as described herein above, rotationalstability of the guiding tool onto a socket in general or an acetabulumor glenoid cavity in particular, may be provided through the provisionof one or more contact elements with contact points which extend overthe rim of the socket (from the inside rim of the socket towards theexterior surface of the bone).

In particular embodiments, the surgical tools as described comprise oneor more contact elements which extend over an angular distance of atleast 30° of the contour of the socket.

In certain embodiments, the one or more lateral contact elements of thesurgical guiding tools as described herein contain, on the surface whichis intended for placement on the bone, patient-specific surfaces, i.e.anatomy engagement surfaces which at least partially match the surfacearound the socket and socket labrum. This implies that the contactelement comprises of a plurality of contact points (corresponding to acontact surface). In particular embodiments, the surgical guiding toolsas described herein comprise only one lateral contact element, which hasa single contact surface extending longitudinally over a section of therim of the socket. In particular embodiments, the contact surface spansthe surface on the exterior of the socket and optionally over the socketlabrum over an angle of at least 30°. In further particular embodiments,the contact element extends longitudinally along the rim of the socketover a stretch corresponding to between 30° and 180°. Alternatively, thesurgical guiding tools as described herein may comprise more than onelateral contact element, each comprising one or more patient-specificcontact surfaces. In particular embodiments, rotational stability of thesurgical guiding tool is obtained by the fact that the contact surfacesof the different lateral contact elements have an arrangement around thesocket and socket labrum, wherein for every pair of adjacent contactpoints not belonging to the same contact surface, the angle between theline drawn between one contact point and the center of the circle bestfitting the socket rim and a second line drawn between the adjacentcontact point and the center is never greater than 180°. Again, asimilar embodiment can be envisaged for a piriform or elliptical socket(glenoid cavity).

Alternative or specific combinations of the above are also envisaged. Incertain embodiments, as indicated above, the surgical guiding tools asdescribed herein may comprise only one lateral contact element, whichcomprises several patient-specific contact surfaces. In otherembodiments, the surgical guiding tools as described herein may compriseat least two lateral contact elements, each comprising one or morepatient-specific contact surfaces as described herein above. In certainembodiments, the surgical guiding tools as described herein may comprisethree or more lateral contact elements, each comprising one or morepatient-specific contact surfaces as described herein above. It will beunderstood to the skilled person that, in the guiding tools as describedherein the different lateral contact elements need not make contact withthe anatomy in the same way and need not contact the anatomy over theirentire surface.

In particular embodiments, it can be envisaged that at least one lateralcontact element is positioned on the guiding tool such that, when placedon the socket rim, its patient-specific surface corresponds to thesurface of the corresponding socket in the location of a conspicuousanatomical feature around the socket labrum. For the glenoid cavity,this can be for example the coracoid process (processus coracoideus);this is a small hook-like structure on the lateral edge of the superioranterior portion of the scapula. For the acetabulum, this can be forexample the posterior notch of the transverse ligament, hereinafter alsoreferred to as “posterior notch”. The provision of a contact elementwhich fits into or against such a feature such as the posterior notch orthe coracoid process further ensures a stable positioning of thesurgical guiding tool onto the socket. Thus, in particular embodiments,the surgical guiding tools as described herein are designed such thatthey comprise at least one lateral contact element which interacts withan anatomical feature on the anatomy surrounding the socket labrum. Inparticular embodiments, the lateral contact element is to be positionedwithin the posterior notch or the coracoid process.

In particular embodiments, the surgical guiding tools as describedherein further comprise a positioning element. The positioning elementis a part of the guiding tool which is used for use with an alignmenttool. In particular embodiments, the positioning element is designed toallow placing an alignment element onto or into the socket or the bonesurrounding the socket in a pre-operationally planned position. The bonesurrounding the socket suitable for placing the alignment element maybe, for example, the bone in the periglenoidal region (e.g.infraglenoidal tuberculum, supraglenoidal tuberculum and collumscapulae, etc.) or periacetabular region (e.g. the limbus acetabuli,sulcus supraacetabularis, superior ramus, etc.). Therefore, thepositioning element may be provided with at least one hole or slit whicheither guides or allows the insertion of an alignment element, such as apin. In particular embodiments, the positioning element is designed foruse with alignment means such as a laser. In these embodiments, thepositioning element can be either a physical shape or an electronicdevice such as a sensor.

In particular embodiments, the central contact element, the lateralcontact element(s) and the positioning element in the surgical guidingtool, allow for the correct positioning of an alignment element.

The desired position of the alignment element for guiding the placementof an implant is determined by pre-operative planning. Moreover, usingpreoperative planning, optimal contact points for the lateral contactelement(s) of the surgical guiding tool as described herein can bedetermined. Indeed, while the number and shape of the contact elementsmay vary, the contact points or surfaces provided thereon determine thestability of the guiding tool. The optimal position of the contactpoints/surfaces ensures positional stability of the surgical guidingtool onto the socket.

In particular embodiments, the positioning element is located on thecentral contact element. More particularly, the central contact elementcomprises a hole which serves as a positioning element.

In particular embodiments, the surgical guiding tools as describedherein allow correct positioning of an alignment element by way of apositioning element. The positioning element may thus comprises anopening or hole which allows the insertion of an alignment element whichis guided by the positioning element into the socket or into the bonesurrounding the socket. The alignment element may be a wire, pin, screwor drill, particularly a metal wire, pin, screw or drill. In particularembodiments, the alignment element is a wire or a pin, particularly aKirschner wire (K-wire) or a Hoffmann pin.

In order to allow the guiding of the positioning of an implant for asocket of a ball-joint, the alignment element is typically positioned onthe socket or on the bone of surrounding the socket in a directionparallel to the installation direction of the implant. The optimalorientation of the opening of the positioning element can be obtained bydetermining the orientation of the positioning element according topre-operational planning. Thus, in certain embodiments, the directionand/or the position of at least one hole of the surgical guiding toolsas described herein which allows the insertion of an alignment elementis in accordance with pre-operational planning. This allows the use ofstandard alignment elements such as K-wires. The positioning and/ororientation of the hole can be obtained via a certain location and/ororientation of the positioning element relative to the rest of thesurgical guiding tool, via a certain location and/or position of thehole in the positioning element, or via a combination of the two.Additionally or alternatively, the shape of the alignment element itselfcan be provided such that, when inserted into the positioning element,it ensures the correct orientation to guide the implant.

As described herein above, the central contact element and the lateralcontact element(s) may contact different areas of the anatomy of thesocket. In particular embodiments, it can be of interest to avoidcontact with the socket labrum. To this end, it can be envisaged thatthe contact elements as well as any connections between the lateral andcentral contact elements “bridge” the labrum. In further embodiments,the contact elements may extend over at least part of the labrum and anadjoining section of the interior surface of the socket and/or exteriorsurface of the bone comprising the socket. In particular embodiments,the contact element(s) contact(s) only the exterior surface of the bonecomprising the socket.

In particular embodiments, the central and lateral contact elements areinterconnected. More particularly, the connecting structures betweenthese elements are selected such as to ensure stable connection whilereducing visual impairment during surgery. Thus in particularembodiments, each lateral contact element is discretely connected to thecentral contact element. Where the lateral contact elements extend overa larger section of the rim (i.e. more than) 10° two or more discreteconnections with the central contact element may be provided. In certainembodiments, the surgical guiding tools as described herein comprise aconnecting structure, wherein the one or more lateral and centralcontact elements extend from the connecting structure. In furtherembodiments, two or more contact elements extend from the connectingstructure. In certain embodiments, the connecting structure is a centralelement, particularly a central axis. In particular embodiments, thecontact element(s) and/or the positioning element(s) are separate unitswhich are connectable to the connecting structure, central element oraxis. In alternative embodiments, the surgical guiding tools asdescribed herein are manufactured as a single piece. In particularembodiments, the connecting structure incorporates the positioningelement and/or the central contact element.

The surgical guiding tools as described herein may further containadditional features, such as guiding features or handling features.Guiding features may be used to guide a surgical tool, such as a drillor a blade. Handling features are used for the manual handling andpositioning of the device and can include features such as knobs (e.g.for holding the tool), dents (e.g. for applying pressure to the toolwhen pushing it into position), hooks or other attachment features (forattachment of other tools) etc. The presence of such dedicated featuresis not critical.

Further provided herein are methods for the manufacture or generation ofthe surgical guiding tools described herein. The surgical guiding toolsdescribed herein comprise contact elements, the position of which isadjusted to correspond to the specific anatomy of the patient.

In particular embodiments as described above, the surgical guiding toolsas described herein comprise patient-specific contact points and/orsurfaces. The generation of patient-specific surgical guiding tools isdone based on pre-operative images of the anatomy surrounding the socketof the joint under consideration, and planning of the surgery. Moreparticularly, the generation of patient-specific surgical guiding toolsis done based on preoperative images of the socket, and planning of thesurgery. Accordingly, methods for producing the surgical guiding toolsas described herein typically comprise the steps of: a) obtaining volumeinformation of the socket of a ball-and-socket joint from a patient; b)obtaining the installation direction of a socket implant for thepatient; c) identifying and selecting parts of the bone surrounding thesocket which are suitable for lateral contact elements; d) designing andgenerating a surgical guiding tool based on the information obtained insteps a), b) and c).

More particularly, the surgical guiding tool designed in step (d)comprises a central contact element which fits onto an area within thesocket of the ball-and-socket joint; one or more lateral contactelements which fit onto the rim of the socket and/or the bonesurrounding the socket and/or the ligament around the socket; and apositioning element provided with a feature, such as an opening, whichallows the interaction with an alignment tool.

Generating the guiding instrument may include designing a model of aguiding instrument or an image thereof. The design of the guidinginstrument may further be provided on an information carrier or can besent to a manufacturing facility for the manufacturing of the guidinginstrument or parts thereof. In particular embodiments, the methodsdescribed herein include manufacturing the guiding instrument or partsthereof.

The step of obtaining volume information of the socket typicallycomprises obtaining digital patient-specific image information which canbe done by any suitable means known in the art, such as for example acomputer tomography (CT) scanner, a magnetic resonance imaging (MRI)scanner, an ultrasound scanner, or a combination of Roentgenograms. Asummary of medical imaging has been described in “Fundamentals ofMedical imaging”, by P. Suetens, Cambridge University Press, 2002. In aparticular embodiment, Additive Manufacturing (AM) techniques are usedfor manufacturing the surgical guiding tools as described herein, orparts thereof. AM techniques are particularly useful to manufacturepatient-specific contact surfaces, or to produce the surgical guidingtools in one piece. As an example, the manufacturing ofmedical-image-based patient-specific surgical instruments via AM isdescribed in U.S. Pat. No. 5,768,134 (Swaelens et al).

AM can be defined as a group of techniques used to fabricate a tangiblemodel of an object typically using three-dimensional (3-D) computeraided design (CAD) data of the object. Currently, a multitude ofAdditive Manufacturing techniques is available, includingstereolithography, Selective Laser Sintering, Fused Deposition Modeling,foil-based techniques, etc. Selective laser sintering uses a high powerlaser or another focused heat source to sinter or weld small particlesof plastic, metal, or ceramic powders into a mass representing the3-dimensional object to be formed. Fused deposition modeling and relatedtechniques make use of a temporary transition from a solid material to aliquid state, usually due to heating. The material is driven through anextrusion nozzle in a controlled way and deposited in the required placeas described among others in U.S. Pat. No. 5,141,680. Foil-basedtechniques fix coats to one another by means of gluing or photopolymerization or other techniques and cut the object from these coatsor polymerize the object.

Typically AM techniques start from a digital representation of the 3-Dobject to be formed. Generally, the digital representation is slicedinto a series of cross-sectional layers which can be overlaid to formthe object as a whole. The AM apparatus uses this data for building theobject on a layer-by-layer basis. The cross-sectional data representingthe layer data of the 3-D object may be generated using a computersystem and computer aided design and manufacturing (CAD/CAM) software.

The surgical guiding tools as described herein may be manufactured indifferent materials. Typically, only materials that are biocompatible(e.g. USP class VI compatible) with the animal or human body are takeninto account. Preferably the surgical guiding tool is formed from aheat-tolerable material allowing it to tolerate high-temperaturesterilization. In the case selective laser sintering is used as an AMtechnique, the surgical template may be fabricated from a polyamide suchas PA 2200 as supplied by EOS, Munich, Germany or any other materialknown by those skilled in the art may also be used.

Also provided herein are methods for using surgical guiding tools suchas those characterized by the features described herein. Moreparticularly, methods are provided for placing an alignment element intoa socket or into the bone surrounding a socket. The methods comprise thesteps of:

-   -   (i) positioning a surgical guiding tool as described herein onto        the socket;    -   (ii) using the feature provided by the positioning element of        the guiding tool provide an alignment tool into or on the bone        of or around the socket;    -   (iii) removing the guiding tool from the socket.

In particular embodiments, the alignment tool is an alignment element,such as a pin. In further embodiments, the alignment element ismaintained in the bone during removal of the guiding tool from thesocket.

Also provided herein are methods for guiding an implant in a socket of aball joint such as an acetabulum or glenoid cavity. These methods maycomprise steps (i), (ii) and (iii) as described herein above and furthercomprise the step of:

(iv) Using the alignment element positioned in the bone to obtain thecorrect implant direction; in particular embodiments this is thedirection according to the preoperational planning.

It is noted that the alignment element envisaged in the present contextmay be used as a visual alignment element or a physical alignmentelement. In particular embodiments, the alignment element is a pin orwire and is used as a physical alignment element to guide an implant orimplant guide onto the bone in the correct position. Typically theimplant or implant guide will comprise a hole or slit which ispositioned such that, when the hole or slit of the implant or implantguide is mated with the alignment feature, it will guide the implantand/or implant guide directly in the desired position on the socket ofthe ball joint.

EXAMPLE

FIG. 1 shows a perspective view (A) of a ball-and-socket joint (3) andthe glenoid cavity (2) of a ball-and-socket joint (3). A surgicalguiding tool (1) as described herein is positioned onto a glenoid cavity(2) of a ball-and-socket joint (3).

The surgical guiding tool typically comprises as central contact element(10) which fits onto the inner surface of the socket of theball-and-socket joint; one or more lateral contact elements (11) whichfit onto the bone surrounding the socket and are positioned within thecoracoid process (14); and a positioning element (12) provided with anopening which allows the insertion of the alignment element.

FIG. 2A shows a side view of a surgical guiding tool (1) according to aparticular embodiment as described herein, positioned on a glenoidcavity (2) of the ball-and-socket joint (3). Also shown is an example ofan alignment element (13) which can be inserted into the positioningelement (12). FIG. 2B shows the top view of the surgical guiding tool(1) according to a particular embodiment, positioned on a glenoid cavity(2) of a ball-and-socket joint (3). FIG. 3 shows the surgical guidingtool (1) according to a particular embodiment as described herein, moreparticularly as seen from different angles.

FIG. 4 illustrates a glenoid (3) for which a contour line (5) and outercontour surface (4) has been determined. This anatomical information isused for generating a patient-specific surgical guiding tool accordingto particular embodiments as described herein. In these embodiments, theone or more lateral contact elements extend longitudinally over asection of rim of the glenoid cavity and extend transversally over therim of the glenoid cavity (i.e. from the inner surface to the outersurface of the bone).

FIG. 5 illustrates the design of a surgical guiding tool (1) accordingto an embodiment envisaged herein. In this embodiment, the tool (1)comprises only one lateral contact element (11) which extendslongitudinally over a section of the rim of the socket and extendstransversally over the rim of the glenoid cavity. The lateral contactelement (11) is connected to the central contact element (12) in twopoints.

What is claimed is:
 1. A patient-specific surgical guiding tool forpositioning an alignment element, the patient-specific guiding toolcomprising: a central contact element configured to fit onto an area ofa socket of a ball-and-socket joint; one or more lateral contactelements configured to fit onto at least one of the following: a rim ofthe socket, a bone surrounding the socket, and a ligament around thesocket, wherein at least one of the one or more lateral contact elementsis configured to fit onto a coracoid process of the ball-and-socketjoint; and a positioning element comprising a feature configured toreceive the alignment element, wherein at least one of the one or morelateral contact elements comprises a contact surface corresponding to atleast part of an outer contour of the socket and the central contactelement comprises a contact surface corresponding to at least part of aninner surface of the socket.
 2. The patient-specific surgical guidingtool of claim 1, wherein the rim of the socket defines at least one of asubstantially circular shape or a roughly elliptical shape having acenter defined by a circle best fitting the substantially circular shapeor by an ellipse best fitting the roughly elliptical shape, wherein theone or more lateral contact elements comprises at least two lateralcontact elements configured to contact the socket in at least threecontact points, wherein, for each contact point of the at least threecontact points, an angle between a first line connecting the contactpoint and the center and a second line connecting an adjacent contactpoint and the center is not greater than 180°, wherein the adjacentcontact point is one of the at least three contact points and isadjacent to the contact point in a given direction around the circle orthe ellipse.
 3. The patient-specific surgical guiding tool of claim 1,further comprising a connecting structure, the one or more lateralcontact elements extending from the connecting structure.
 4. Thepatient-specific surgical guiding tool of claim 3, wherein theconnecting structure corresponds with the positioning element.
 5. Thepatient-specific surgical guiding tool of claim 1, wherein at least oneof the one or more lateral contact elements corresponds with ananatomical feature around the socket.
 6. The patient-specific surgicalguiding tool of claim 1, wherein the alignment element comprises atleast one of the following: a pin, a wire, a screw and a drill.
 7. Thepatient-specific surgical guiding tool of claim 1, wherein thepositioning element corresponds to at least one of the central contactelement and the one or more lateral contact elements.
 8. Thepatient-specific surgical guiding tool of claim 1, wherein the socket isa glenoid cavity.
 9. A method of positioning an alignment tool on bone,the method comprising: positioning a surgical guiding tool onto a socketof a ball-and-socket joint, wherein the surgical guiding tool comprises:a central contact element configured to fit onto an area of the socket;one or more lateral contact elements configured to fit onto at least oneof the following: a rim of the socket, a bone surrounding the socket,and a ligament around the socket, wherein at least one of the one ormore lateral contact elements is configured to fit onto a coracoidprocess of the ball-and-socket joint; and a positioning elementcomprising a feature configured to receive the alignment tool;positioning the alignment tool on or into the bone of or around thesocket by inserting it through an aperture defined by the positioningelement; and removing the surgical guiding tool from the socket.
 10. Themethod of claim 9, wherein the alignment tool comprises a pin and stepalignment element, and wherein removing the surgical guiding toolfurther comprises removing the surgical guiding tool from the socketalong a direction of a longitudinal axis of the alignment elementwithout removing the alignment element from the bone.